Also, images must be larger than 20 bytes in size. Smaller images reduces the correctness of results.

There is no limitation on the maximum size of image. It can be as large as you want but your browser/system can hang in case you put images of over 3-4 mb in size.

No image filters. You can drag and drop objectionable images and you’ll get images visually similar to that. No only this, if you search for a visually similar images to a ‘b_kini’ girl you might see a ‘n_de’ image in search result.

Google search by image has over dependency on color and contrast of the image. If you’ll put a black and white image then the search results would be unsatisfactory while if you’ll search a colored image then results would be very much correct.

This service commits few horrible mistakes, one such mistake came in light when I drag and dropped image of my friend only to see a list of animals in ‘visually similar images’ section of in search results.

You can try these by yourself and I’m pretty sure you’ll echo the same – The service is good, but not anywhere near to perfection.